This invention relates to dyes, to inks and to their use in ink jet printing (xe2x80x9cIJPxe2x80x9d). IJP is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate.
There are many demanding performance requirements for dyes and inks used in IJP. For example they desirably provide sharp, non-feathered images having good water-fastness, light-fastness and optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzle.
According a first aspect of the present invention there is provided a compound of Formula (1): 
wherein:
A is N, Cxe2x80x94Cl, Cxe2x80x94CN or Cxe2x80x94NO2;
L1 is xe2x80x94OR3;
Z is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NR2xe2x80x94;
R1 and R2 are each independently H or optionally substituted alkyl;
R3 is H or alkyl;
each W independently is xe2x80x94CO2Q or xe2x80x94SO3Q;
each X independently is an optionally substituted amino group or a group which is substituted by an optionally substituted amino group;
each Y independently is a substituent other than those defined for W and X;
each Q independently is ammonium or substituted ammonium;
m, n and p each independently have a value of from 0 to 3; and
(m+n+p) has a value of from 0 to 5.
Preferably A is N.
Preferably m, n and p each independently have a value of 0 or 1.
Preferably n is 1 when m is 0
Preferably (m+n+p) has a value of 1, 2 or 3, more preferably 1 or 2.
Z is preferably xe2x80x94NR2xe2x80x94, more preferably xe2x80x94NHxe2x80x94.
Preferably each Y independently is halo, more preferably F or Cl; hydroxy; nitro; cyano; optionally substituted alkyl, preferably optionally substituted C1-10-alkyl, especially C1-4-alkyl; optionally substituted alkoxy, preferably optionally substituted C1-10-alkoxy, more preferably C1-4-alkoxy; optionally substituted aryl, preferably optionally substituted phenyl or optionally substituted naphthyl; optionally substituted aralkyl, preferably optionally substituted C7-12-aralkyl, more preferably phenyl-(C1-6-alkylene)-, especially phenyl-xe2x80x94CH2xe2x80x94; xe2x80x94SRa; xe2x80x94CORa; xe2x80x94COORa; SO3Ra; xe2x80x94SO2Ra; or xe2x80x94SORa; wherein Ra is optionally substituted C1-4-alkyl; wherein the optional substituents are selected from carboxy, sulpho, hydroxy, nitro, cyano and halo.
R1 and R2 are preferably each independently H or optionally substituted C1-4-alkyl, more preferably H, C1-4-alkyl or C2-4-alkyl substituted by hydroxy, carboxy, sulpho or cyano. Examples include methyl, ethyl, n-propyl, iso-propyl, hydroxyethyl, cyanoethyl, sulphopropyl and carboxyethyl. It is especially preferred that R1 and R2 are H.
Preferably the compounds of Formula (1) are monoazo compounds (i.e. they contain only one azo (xe2x80x94Nxe2x95x90Nxe2x80x94) group).
R3 is preferably H or C1-10-alkyl, more preferably H or C1-6alkyl, especially H or C1-4-alkyl, more especially H.
When X is, or is substituted by, an optionally substituted amino group, the optionally substituted amino group preferably has a pKa of from 12 to 4, more preferably of from 10 to 6.
The optionally substituted amino groups referred to in the definition of X are preferably of the formula xe2x80x94NR4R5 wherein R4 and R5 are each independently H or optionally substituted alkyl; or R4 and R5 together with the nitrogen atom to which they are attached form a 5- or 6-membered ring.
When R4 or R5 is optionally substituted alkyl it is preferably optionally substituted C1-6-alkyl, more preferably optionally substituted C1-4-alkyl. Preferred substituents are selected from carboxy, sulpho, hydroxy, amino and C1-4-alkoxy.
When R4 and R5 together with the nitrogen to which they are attached form an optionally substituted 5- or 6-membered ring they preferably form optionally substituted morpholine, more preferably optionally substituted piperazine. The substituents are preferably selected from hydroxy, carboxy, sulpho, C1-6-alkoxy, C1-6-alkyl and C1-6-alkyl substituted by hydroxy, carboxy, sulpho or an optionally substituted amino group.
A preferred substituted morpholine or piperazine ring carries a group of the formula xe2x80x94Mxe2x80x94NR6R7 wherein M is an alkylene linking group and R6 and R7 are each independently H, C1-6-alkyl or C1-6-alkyl substituted by hydroxy, carboxy, sulpho, amino or C1-4-alkoxy.
M is preferably C1-6-alkylene, more preferably C2-6-alkylene and especially xe2x80x94(CH2)gxe2x80x94, where g is from 2 to 6.
An especially preferred substituted piperazinyl group is of the Formula (2): 
wherein M, R6 and R7 are as hereinbefore defined.
Preferred groups of the Formula (2) include 
Examples of optionally substituted amino groups include: xe2x80x94NH2, xe2x80x94NHCH2CH3, xe2x80x94N(CH2CH3)2, xe2x80x94NHCH2CH2OH:
xe2x80x94NH(CH2)2N(CH3)2, xe2x80x94NH(CH2)2N(CH3)2, 
When X is a group which is substituted by an optionally substituted amino group it preferably comprises optionally interrupted alkylene carrying a xe2x80x94NR4R5 group wherein R4 and R5 are as hereinbefore defined.
Preferably the optionally interrupted alkylene group comprise one, two or three C2-10-alkylene chains and 0, 1, 2, 3 or 4 interrupting groups selected from O, CO, CO2, S, SO, SO2, NH, optionally substituted phenylene, CONH and SO2NH. The interrupting groups may link each of the C2-10-alkylene chains and/or be at a terminal position in the interrupted alkylene chain.
Preferred interrupted alkylene groups having one C2-10-alkylene chain and one interrupting group are of the formula xe2x80x94SO2NHxe2x80x94(C2-10-alkylene)-; xe2x80x94NHSO2(C2-10-alkylene)xe2x80x94; xe2x80x94CONHxe2x80x94(C2-10-alkylene)xe2x80x94; xe2x80x94NHCOxe2x80x94(C2-10-alkylene)xe2x80x94; xe2x80x94[(O, S or NH)xe2x80x94C2-10-alkylene]xe2x80x94; xe2x80x94SOxe2x80x94(C2-10-alkylene)xe2x80x94; and SO2xe2x80x94(C2-10-alkylene)xe2x80x94.
Preferred interrupted alkylene groups having two C2-10-alkylene chains and two interrupting groups are any two of the groups described in the previous paragraph attached together, especially xe2x80x94SO2xe2x80x94(C2-10-alkylene)xe2x80x94NHxe2x80x94(C2-10-alkylene)xe2x80x94.
Q is preferably of the formula +NT4 wherein each T independently is H or optionally substituted alkyl, or two groups represented by T are H or optionally substituted alkyl and the remaining two groups represented by T, together with the N atom to which they are attached, form a 5- or 6-membered ring (preferably a morpholine, pyridine or piperidine ring).
Preferably each T independently is H or C1-4-alkyl, more preferably H, CH3 or CH3CH2, especially H. Thus Q is preferably ammonium (i.e. +NH4).
Examples of groups represented by Q include +NH4, morpholinium, piperidinium, pyridinium, (CH3)3N+H, (CH3)2N+H2, H2N+(CH3)(CH2CH3),CH3N+H3, CH3CH2N+H3, H2N+(CH2CH3)2, CH3CH2CH2N+H3, CH3CH2CH2N+H3, (CH3)2CHN+H3, N+(CH3)4, N+(CH2CH3)4, N-methyl pyridinium, N,N-dimethyl piperidinium and N,N-dimethyl morpholinium.
A first preferred embodiment of the present invention comprises a compound of the Formula (1) and salts thereof wherein:
A is N;
m is 0, 1 or 2;
n is 0 or 1;
p is 0 or 1;
X is of the formula xe2x80x94NR4R5 or a group which is substituted by xe2x80x94NR4R5;
Y is halo, hydroxy, cyano, C1-4-alkyl, C1-4-alkoxy, xe2x80x94SRa, xe2x80x94CORa, xe2x80x94COORa, xe2x80x94SO3Ra, xe2x80x94SO2Ra or SORa; and
R1, R2, R3, R4, R5, Ra, Q and W are as hereinbefore defined.
In the first preferred embodiment it is especially preferred that Y is C1-4-alkyl.
A second preferred embodiment comprises a monoazo compound of the Formula (3): 
wherein:
Z is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NR8xe2x80x94;
R8 is H or C1-4-alkyl optionally substituted by hydroxy, carboxy, sulpho or cyano;
L2 is xe2x80x94OR9;
R9 is H or C1-4-alkyl;
each W independently is xe2x80x94CO2Q or xe2x80x94SO3Q;
each X1 is xe2x80x94NR4R5, xe2x80x94SO2xe2x80x94NR4R5, xe2x80x94SO2(C1-10-alkylene)xe2x80x94NR4R5 or C1-6-alkyl substituted by xe2x80x94NR4R5;
each Y1 independently is Cl, nitro, cyano, C1-10-alkyl, or C1-10-alkyl substituted by hydroxy, carboxy, sulpho, or C1-6-alkoxy;
m, n and p are each independently 0 or 1;
(m+n+p) is 1, 2 or 3; and
Q, R4 and R5 are as hereinbefore defined;
provided that n is 1 when m is 0.
In preferred compounds of Formula (3) R4 and R5 are each independently H or optionally substituted C1-6-alkyl as hereinbefore described, or xe2x80x94NR4R5 is of Formula (2) as hereinbefore defined.
Preferred compounds in the second embodiment comprise a compound of Formula (3) as hereinbefore defined wherein:
Z is xe2x80x94NR8xe2x80x94;
Y1 is C1-6-alkyl;
L2 is xe2x80x94OH or methoxy; and
R8, W, X1, m, n, p, R4 and R5 are as hereinbefore defined, provided that n is 1 when m is 0.
The compounds of Formula (1) and (3) may be made from corresponding compounds in the free acid or alkali metal salt form using techniques known in the art. For example, an alkali metal salt of a dye may be converted into a salt with ammonia or an amine by dissolving an alkali metal salt of the dye in water, acidifying with a mineral acid and adjusting the pH of the solution to pH 9 to 9.5 with ammonia or the amine and removing the alkali metal cations by dialysis.
The compounds may be prepared in the free acid or salt form using conventional techniques for the preparation of azo dyes. For example a suitable method comprises condensing a compound of the Formula (4) with a compound of the Formula L1H: 
wherein:
R1, Z, A, W, X, Y, m, n, p are as hereinbefore defined.
The condensation is preferably performed in a liquid medium, more preferably an aqueous medium and especially water. Temperatures of 15xc2x0 C. to 100xc2x0 C. are preferred, more preferably from 60 to 90xc2x0 C. Preferably a reaction time of 1 to 48, more preferably 3 to 24 hours is used.
The condensation is preferably performed in the presence of a base. The base may be any inorganic base for example, ammonia, an alkali metal or alkali earth metal hydroxide, carbonate or bicarbonate, or an organic base. Preferred organic bases are tertiary amines for example, N-alkylated heterocycles, for example Nxe2x80x94(C1-4alkyl)morpholine, Nxe2x80x94(C1-4-alkyl)piperidine, N,Nxe2x80x2-di(C1-4-alkyl)piperazine; tri(C1-4-alkyl)amines, for example triethylamine, and optionally substituted pyridines, especially pyridine.
The amount of base used may be varied between wide limits but it is preferred to use less than 40, more preferably less than 10 and especially from 3 to 5 moles for each mole of the compound of Formula (4).
After the condensation the product may be isolated by precipitating the product as a salt from the reaction mixture for example by the addition of a suitable alkali metal salt, especially sodium chloride. Alternatively, the product may be isolated in its free acid form by acidifying the reaction mixture, preferably using a mineral acid, especially hydrochloric acid. Where the product precipitates as a solid it may be separated from the mixture by filtration.
If desired unwanted anions may be removed from the product of the above process by dialysis, osmosis, ultrafiltration or a combination thereof.
The product of the above process may be converted to the ammonium or substituted ammonium salt by the addition of ammonia, ammonium hydroxide, primary, secondary, tertiary or quaternary amine. When the base used in the condensation process is an organic amine an excess may be used so that the compound of Formula (1) is formed as the substituted ammonium salt.
The compound of the Formula (4) may be prepared using conventional techniques, for example by:
(1) diazotising 2-naphthylamine-1-sulphonic acid to give the corresponding diazonium salt;
(2) coupling the diazonium salt from stage (1) with 1-acetamido-8-naphthol-3,6-disulphonic acid at a pH greater than 7, preferably at a pH of from 8 to 9;
(3) alkaline hydrolysis of the product of stage (2) to remove the acetyl group;
(4) condensing the product from stage (1) with a compound of the formula: 
wherein A is as hereinbefore defined; and
(5) condensing the product from stage (4) with approximately 1 molar equivalent of the compound of the formula: 
wherein Z, W, X, Y, m, n and p are as hereinbefore defined.
The diazotisation in stage (1) is preferably performed in an aqueous medium at a pH below 7 in the presence of a suitable diazotisation agent. Dilute mineral acid, e.g. HCl or H2SO4, is preferably used to achieve the desired acidic conditions. Conveniently the diazotisation agent is formed in-situ, for example by dissolving an alkali metal nitrite, preferably sodium nitrite, in a molar excess of mineral acid, preferably HCl. Normally at least one mole of diazotisation agent per mole of 2-naphthylamine-1-sulphonic acid, preferably from 1 to 1.25 moles will be used in the diazotisation.
The temperature of the diazotisation is not critical and may conveniently be carried out at from xe2x88x925xc2x0 C. to 20xc2x0 C., preferably from 0 to 10xc2x0 C. and especially from 0 to 5xc2x0 C.
The hydrolysis in stage (3) is preferably performed at a pH in the range 9 to 14. The temperature during hydrolysis is preferably from 40 to 90xc2x0 C.
According to a second aspect of the present invention there is provided an ink comprising:
(a) from 0.01 to 30 parts of a compound of the Formula (1), or preferably of Formula (3), as hereinbefore defined except that Q is any cation; and
(b) from 70 to 99.99 parts of a medium comprising component (i), (ii) or (iii):
(i) a mixture of water and an organic solvent;
(ii) an organic solvent free from water; or
(iii) a low melting point solid;
wherein all parts are by weight and the number of parts of (a)+(b)=100.
In preferred compounds which may be used in the component (a) of the ink Q is H or an alkali metal, more preferably Q is sodium, ammonium or substituted ammonium. It is especially preferred that Q is ammonium or substituted ammonium as hereinbefore defined in the first aspect of the present invention.
The number of parts of component (a) is preferably from 0.1 to 20, more preferably from 0.5 to 15, and especially from 1 to 5 parts. The number of parts of component (b) is preferably from 99.9 to 80, more preferably from 99.5 to 85, especially from 99 to 95 parts.
When the medium is a mixture of water and an organic solvent or an organic solvent free from water, preferably component (a) is completely dissolved in component (b). Preferably component (a) has a solubility in component (b) at 20xc2x0 C. of at least 10%. This allows the preparation of concentrates which may be used to prepare more dilute inks and reduces the chance of the dye precipitating if evaporation of the liquid medium occurs during storage.
When the medium comprises a mixture of water and an organic solvent, the weight rafio of water to organic solvent is preferably from 99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from 95:5 to 80:20.
It is preferred that the organic solvent present in the mixture of water and organic solvent is a water-miscible organic solvent or a mixture of such solvents. Preferred water-miscible organic solvents include C1-6-alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferably diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol; mono-C1-4-alkyl ethers of diols, preferably mono-C1-4alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether, cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclic esters, preferably caprolactone; sulphoxides, preferably dimethyl sulphoxide and sulpholane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-soluble organic solvents.
Especially preferred water-miscible organic solvents are cyclic amides, especially 2-pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone; diols, especially 1,5-pentane diol, ethyleneglycol, thiodiglycol, diethyleneglycol and triethyleneglycol; and mono-C1-4-alkyl and C1-4-alkyl ethers of diols, more preferably mono- C1-4-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxy-2-ethoxy-2-ethoxyethanol.
A preferred medium comprises:
a) from 75 to 95 parts water; and
b) from 25 to 5 parts in total of one or more solvents selected from diethylene glycol, 2-pyrrolidone, thiodiglycol, N-methylpyrrolidone, cyclohexanol, caprolactone, caprolactam and pentane-1,5-diol;
wherein the parts are by weight and the sum of the parts (a) and (b)=100.
Examples of further suitable ink media comprising a mixture of water and one or more organic solvents are described in U.S. Pat. No. 4,963,189, U.S. Pat. No. 4,703,113, U.S. Pat. No. 4,626,284 and EP 4,251,50A.
When the liquid medium comprises an organic solvent free from water, (i.e. less than 1% water by weight) the solvent preferably has a boiling point of from 30xc2x0 to 200xc2x0 C., more preferably of from 40xc2x0 to 150xc2x0 C., especially from 50 to 125xc2x0 C. The organic solvent may be water-immiscible, water-miscible or a mixture of such solvents. Preferred water-miscible organic solvents are any of the hereinbefore described water-miscible organic solvents and mixtures thereof. Preferred water-immiscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH2Cl2; and ethers, preferably diethyl ether; and mixtures thereof.
When the liquid medium comprises a water-immiscible organic solvent, preferably a polar solvent is included because this enhances solubility of the dye in the liquid medium. Examples of polar solvents include C1-4-alcohols. In view of the foregoing preferences it is especially preferred that where the liquid medium is an organic solvent free from water it comprises a ketone (especially methyl ethyl ketone) and/or an alcohol (especially a C1-4-alkanol, more especially ethanol or propanol).
The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which gives good control over the drying characteristics and storage stability of the ink.
Ink media comprising an organic solvent free from water are particularly useful where fast drying times are required and particularly when printing onto hydrophobic and non-absorbent substrates, for example plastics, metal and glass
Preferred low melting solid media have a melting point in the range from 60xc2x0 C. to 125xc2x0 C. Suitable low melting point solids include long chain fatty acids or alcohols, preferably those with C18-24 chains, and sulphonamides. The dye of Formula (1) or (3) may be dissolved in the low melting point solid or may be finely dispersed in it.
The dyes according to the present invention exhibit a high solubility in aqueous media, accordingly it is preferred that the liquid medium is a mixture of water and one or more water miscible organic solvent(s).
The ink may also contain additional components conventionally used in ink jet printing inks, for example viscosity and surface tension modifiers, pH buffers (e.g. 1:9 citric acid/sodium citrate) corrosion inhibitors, biocides, kogation reducing additives and surfactants which may be ionic or non-ionic.
The presence of impurities in an ink jet printing ink can result in the formation of precipitates in the ink This is undesirable because the precipitates can block the narrow ink jet nozzle in the printer. Therefore, the dye(s) according to the present invention may be, and preferably are, purified to remove undesirable impurities before they are incorporated into inks for ink jet printing. Conventional techniques may be employed for purifying the dyes, for example osmosis and/or dialysis.
A third aspect of the present invention provides a process for printing an image on a substrate comprising applying an ink according to the second aspect of the present invention to the substrate by means of an ink jet printer.
Preferred inks used in this process contain a dye of the Formula (1) or Formula (3) are as defined in the first aspect of the present invention.
The ink jet printer preferably applies the ink to the substrate in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink jet printers are piezoelectric ink jet printers and thermal ink jet printers. In thermal ink jet printers, programmed pulses of heat are applied to the ink in a reservoir by means of a resistor adjacent to the orifice, thereby causing the ink to be ejected in the form of small droplets directed towards the substrate during relative movement between the substrate and the orifice. In piezoelectric ink jet printers the oscillation of a small crystal causes ejection of the ink from the orifice.
The substrate is preferably paper, plastic, a textile, metal or glass, more preferably paper, an overhead projector slide or a textile material, especially paper.
Preferred papers are plain or treated papers which may have an acid, alkaline or neutral character. Examples of commercially available papers include, HP Premium Coated Paper, HP Photopaper (all available from Hewlett Packard Inc), Stylus Pro 720 dpi Coated Paper, Epson Photo Quality Glossy Film, Epson Photo Quality Glossy Paper (available from Seiko Epson Corp.), Canon HR 101 High Resolution Paper, Canon GP 201 Glossy Paper, Canon HG 101 High Gloss Film (all available from Canon Inc.), Wiggins Conqueror paper (available from Wiggins Teape Ltd), Xerox Acid Paper and Xerox Alkaline paper, Xerox Acid Paper (available from Xerox).
A fourth aspect of the present invention provides a paper, an overhead projector slide or a textile material printed with an ink according to the second aspect of the present invention, or by means of the process according to the third aspect of the present invention.
When the substrate is a textile material the ink according to the invention is preferably applied thereto by:
i) applying the ink to the textile material using an ink jet printer; and
ii) heating the printed textile material at a temperature of from 50xc2x0 C. to 250xc2x0 C.
Preferred textile materials are natural, synthetic and semi-synthetic materials. Examples of preferred natural textile materials include wool, silk, hair and cellulosic materials, particularly cotton, jute, hemp, flax and linen. Examples of preferred synthetic and semi-synthetic materials include polyamides, polyesters, polyacrylonitriles and polyurethanes.
Preferably the textile material has been treated with an aqueous pre-treatment composition comprising a thickening agent and optionally a water-soluble base and a hydrotropic agent and dried prior to step i) above.
The pre-treatment composition preferably comprises a solution of the base and the hydrotropic agent in water containing the thickening agent. Particularly preferred pre-treatment compositions are described more fully in European Patent Application No.534660A1.
A fifth aspect of the present invention provides an ink jet printer cartridge containing an ink according to the second aspect of the present invention. The ink jet printer cartridge is optionally refillable.